Coupling module of a modular implantable medical device

ABSTRACT

In an implantable medical device having individual modules, a coupling module couples the modules to one another. The coupling module supports electrical and/or mechanical coupling of the modules. The coupling module may assume a variety of shapes or configurations. The various embodiments of the coupling module may offer the modules varying degrees of freedom of movement relative to one another.

This application is a continuation of U.S. application Ser. No.10/731,699, filed Dec. 9, 2003, the entire content of which isincorporated herein by reference.

Application Ser. No. 10/731,699 claims the benefit of:

1. U.S. Provisional Application entitled “CRANIAL NEUROSTIMULATOR ANDMETHOD,” Ser. No. 60/431,854, (Attorney Docket No. P-10891.00), filed onDec. 9, 2002;2. U.S. Provisional Application entitled “Implantable Cranial MedicalDevices and Methods,” Ser. No. 60/471,262, (Attorney Docket No.P-11462.00), filed on May 16, 2003;3. U.S. Provisional Application entitled “IMPLANTABLE CRANIAL MEDICALDEVICES AND METHODS,” Ser. No. 60/503,945, (Attorney Docket No.P-11696.00), filed on Sep. 20, 2003;4. U.S. Provisional Application entitled “IMPLANTABLE CRANIAL MEDICALDEVICES AND METHODS,” Ser. No. 60/503,946, (Attorney Docket No.P-11697.00), filed on Sep. 20, 2003; and5. U.S. Provisional Application entitled “Thin Neuro Stimulation System,Device and Method,” Ser. No. 60/507,857, (Attorney Docket No.P-20211.00), filed on Oct. 1, 2003. The entire content of each of theseU.S. Provisional Applications is incorporated herein by reference.

The following co-pending and commonly-assigned U.S. patent applications,filed on even date with U.S. application Ser. No. 10/731,699, are alsoincorporated herein by reference in their entirety:

1. U.S. patent application Ser. No. 10/731,869 entitled “MODULARIMPLANTABLE MEDICAL DEVICE,” to Carl D. Wahlstrand et al., filed Dec. 9,2003, assigned Attorney Docket No.: 1023-318US01/P-10891.00;2. U.S. patent application Ser. No. 10/731,868 entitled “IMPLANTATION OFLOW-PROFILE IMPLANTABLE MEDICAL DEVICE,” to Ruchika Singhal et al.,filed Dec. 9, 2003, assigned Attorney Docket No.:1023-330US01/P-11795.00;3. U.S. patent application Ser. No. 10/730,873 entitled “OVERMOLD FOR AMODULAR IMPLANTABLE MEDICAL DEVICE,” to Ruchika Singhal et al., filedDec. 9, 2003, assigned Attorney Docket No.: 1023-332US01/P-11798.00;4. U.S. patent application Ser. No. 10/731,881 entitled “REDUCINGRELATIVE INTER-MODULE MOTION IN A DISTRIBUTED MODULAR IMPLANTABLEMEDICAL DEVICE,” to Carl D. Wahlstrand et al., filed Dec. 9, 2003,assigned Attorney Docket No.: 1023-333US01/P-11797.00;5. U.S. patent application Ser. No. 10/730,878 entitled “LEAD CONNECTIONMODULE OF A MODULAR IMPLANTABLE MEDICAL DEVICE,” to Ruchika Singhal etal., filed Dec. 9, 2003, assigned Attorney Docket No.:1023-334US01/P-11799.00;6. U.S. patent application Ser. No. 10/730,877 entitled “LOW-PROFILEIMPLANTABLE MEDICAL DEVICE,” to Darren A. Janzig et al., filed Dec. 9,2003, assigned Attorney Docket No.: 1023-335US01/P-11801.00; and

7. U.S. patent application Ser. No. 10/731,867 entitled “CONCAVITY OF ANIMPLANTABLE MEDICAL DEVICE,” to Carl D. Wahlstrand et al., filed Dec. 9,2003, assigned Attorney Docket No.: 1023-336US01/P-11800.00.

8. U.S. patent application Ser. No. 10/731,638 entitled “MODULARIMPLANTABLE MEDICAL DEVICE,” to Carl D. Wahlstrand et al., filed Dec. 9,2003, assigned Attorney Docket No.: 1023-342US01/P-20542.00.

TECHNICAL FIELD

The invention relates to medical devices, and more particularly, toimplantable medical devices that deliver therapy to and/or monitor apatient.

BACKGROUND

Depending on the application for which they are implanted in a patient,implantable medical devices (IMDs) may include a variety of electricaland/or mechanical components. Typically, an IMD includes a rigid housingthat houses all of its components, which are generally fragile, toprotect the components from forces to which they would otherwise beexposed when implanted within the human body. In order to avoidpotentially harmful interactions between the components and bodilyfluids, e.g., corrosion, IMD housings are typically hermetically sealed.Many IMD housings are fabricated from titanium because of its desirablerigidity and biocompatibility.

The size and shape of an IMD housing is dependant on the sizes andshapes of the components of the IMD. Large components common to mostIMDs include a battery, a telemetry coil, and a hybrid circuit thatincludes digital circuits, e.g., integrated circuit chips and/or amicroprocessor, and analog circuit components. Attempts have been madeto reduce the size of the IMD housing by reducing the size of thesecomponents, changing the shape of these components, and organizing thesecomponents within the IMD housing to avoid empty space within thehousing. Despite these efforts to reduce the size of IMD housings, thesize, shape and rigidity of IMD housings still greatly limits thelocations within the human body where an IMD can be practicallyimplanted.

Due to these limitations, an IMD is typically implanted within theabdomen, upper pectoral region, or subclavicular region of a patient.Leads or catheters must be used in order to deliver therapy or monitor aphysiological parameter at a location of the body other than where theIMD is implanted. Implantation and positioning of leads and catheterscan be difficult and time-consuming from the perspective of a surgeon,particularly where the IMD is located a significant distance from thetreatment or monitoring site. Moreover, the increased surgical time,increased surgical trauma, and increased amount of implanted materialassociated with the use of leads and catheters can increase the risk tothe patient of complications associated with the implantation of an IMD.

For example, IMDs that are used to treat or monitor the brain, e.g., todeliver deep brain stimulation (DBS) therapy, are implanted somedistance away from the brain, e.g., within the subclavicular region ofpatients. The long leads that connect the implantable medical device toelectrodes implanted within the brain require tunneling under the scalpand the skin of the neck, thereby requiring increased surgery and aprolonged amount of time under general anesthesia during the implantprocedure. The lengthy tract along the leads is more susceptible toinfection, and the leads can erode the overlying scalp, forcing removalso that the scalp can heal. Further, the long leads running under thescalp and through the neck are more susceptible to fracture due totorsional and other forces caused by normal head and neck movements.

SUMMARY

In general, the invention relates to a coupling module for a modularimplantable medical device. In order to provide an implantable medicaldevice with a smaller profile so that the IMD can better fit intoavailable body locations, various functional components of the IMD areseparated into individual interconnected modules. This modulararchitecture for the implantable medical device permits the devicefootprint to be distributed over a larger area while making the profilesmaller.

The multiple modules and their respective flexible interconnections aretypically coupled to one another mechanically and electrically.Electrical coupling permits the modules to receive power or signals fromone another, for example. Mechanical coupling helps constrain themodules while also providing some freedom of movement. In general, it isdesirable that a modular IMD include some freedom of movement, so thatthe IMD may conform to the body location into which it is to beimplanted. The present invention is directed to one or more couplingmechanisms for the modular component modules within the implantablemedical device. The coupling mechanisms support mechanical andelectrical coupling of the modules.

In one embodiment, the invention is directed to an implantable medicaldevice that includes at least two modules, each of the modulescomprising a housing. The IMD also includes a coupling module coupled toeach of the modules. The coupling module defines at least one lumenbetween the modules and permits motion of the two modules along at leastone axis of motion.

In another embodiment, the invention presents a device comprising afirst module that includes control electronics comprising a firsthousing, a second module comprising a second housing, and a couplingmodule fixedly coupled to the first and second housings. The couplingmodule defines at least one lumen and permits motion of the firsthousing relative to the second housing and along at least one axis ofmotion. The coupling module may assume a variety of configurations. Thecoupling module may include, for example, multiple lumens, a shapedcross-section or a helical portion.

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1A and 1B are diagrams illustrating use of an implantable medicaldevice in a patient according to an example embodiment of the presentinvention.

FIG. 2 is a schematic diagram illustrating an implantable medical deviceaccording to another embodiment of the present invention.

FIGS. 3A and 3B are schematic diagrams illustrating an implantablemedical device according to another embodiment of the present invention.

FIGS. 4A-4F are schematic diagrams illustrating various orientations ofmultiple modules within an implantable medical device according tovarious embodiments of the present invention.

FIG. 5A is a schematic diagram illustrating the construction of anovermold and modules used in construction of an implantable medicaldevice according to the present invention.

FIG. 5B is an exploded view of an embodiment of the overmold and modulesshown in FIG. 5A.

FIG. 5C is a side view of an embodiment of the overmold and modulesshown in FIG. 5A.

FIGS. 6A-6C are schematic diagrams illustrating distributed modules anda coupling module with a single degree of freedom of motion according toan embodiment of the present invention.

FIGS. 7A-7B are schematic diagrams illustrating distributed moduleshaving a one or more coupling modules with two degrees of freedom ofmotion according to an embodiment of the present invention.

FIG. 8 is schematic diagram illustrating distributed modules having acoupling module with three degrees of freedom of motion according to anembodiment of the present invention.

FIG. 9 is schematic diagram illustrating distributed modules having acoupling module having a hermetic and non-hermetic interconnectionaccording to an embodiment of the present invention.

FIGS. 10A-10I are schematic diagrams illustrating exemplary shapes,configurations and features of a coupling module according toembodiments of the present invention.

FIGS. 11A-11M are schematic diagrams illustrating configurations ofmultiple modules and a coupling module according to embodiments of thepresent invention.

FIGS. 12A-12C are schematic diagrams illustrating module interfaces witha coupling module according to an embodiment of the present invention.

FIG. 13 is a schematic diagram illustrating the axes of motion presentin a multi-module implantable medical device.

FIGS. 14A-14C are a schematic diagrams illustrating motion restrictionof a multi-module implantable medical device.

FIGS. 15A-15B are schematic diagrams illustrating the interaction ofcomponents of an implantable medical device that are part of an overmoldaccording to the present invention.

FIGS. 16A-16B are a perspective diagrams illustrating a multi-moduleimplantable medical device having an triangular module arrangement and acoupling module according to the present invention.

DETAILED DESCRIPTION

FIGS. 1A and 1B are diagrams illustrating use of an implantable medicaldevice (IMD) in a patient according to an example embodiment of thepresent invention. An IMD101 is implanted within a patient 100 in orderto permit IMD101 to provide therapies to the patient 100. In the exampleillustrated within FIGS. 1A-1B, IMD101 is implanted under the scalp ofthe patient 100 in order to locate the device 101 as close as possibleto the location of leads 102 that provide the therapy.

FIG. 1A shows patient 100 with IMD 101 deployed beneath his scalp. InFIG. 1A, IMD 101 is a neurostimulator that provides deep brainstimulation via leads 102 deployed in the brain of patient 100. IMD 101is deployed in proximity to site of stimulation therapy. IMD 101 may beused to treat any nervous system disorder including, but not limited to,epilepsy, pain, psychological disorders including mood and anxietydisorders, movement disorders (MVD) such as, but not limited to,essential tremor and Parkinson's disease and neurodegenerativedisorders.

Although IMD 101 is depicted as a neurostimulator, the invention is notlimited to applications in which the IMD is a neurostimulator. Theinvention may be employed with IMDs that perform any monitoring ortherapeutic functions. The invention is not limited to IMDs that includeleads deployed in the brain, but may also be employed with leadsdeployed anywhere in the head or neck including, for example, leadsdeployed on or near the surface of the skull, leads deployed beneath theskull such as near or on the dura mater, leads placed adjacent cranialor other nerves in the neck or head, or leads placed directly on thesurface of the brain. Nor is the invention limited to IMDs that arecoupled to electrodes. The invention may be employed with IMDs coupledto any sensing or therapeutic elements, such as temperature sensors ormotion sensors. The invention may also be employed with different typesof IMDs including, but not limited to, IMDs operating in an open loopmode (also referred to as non-responsive operation), IMDs operating in aclosed loop mode (also referred to as responsive), and IMDs forproviding monitoring and/or warning.

In general, IMD 101 has a low profile, i.e., IMD 101 is thin to permitIMD 101 to be deployed effectively, comfortably and cosmetically andunder the scalp. In one embodiment of the invention, IMD 101 has amaximum thickness of between approximately 4 millimeters andapproximately 8 millimeters. The use of a reduced profile may reduce therisk of infection, skin erosion and cosmetic issued related to theimplantation of IMD 101.

Many locations within a patient do not present adequate profile forimplantable medical devices. As such, many uses of such devices employlengthy leads located remote from an implantation site of the IMD. Theuse of these lengthy leads requires complicated insertion proceduresfrom the site of the IMD to the site of lead deployment that may causemedical complications to the patient as well as may lead to failures inconnection leads. By constructing IMD 101 as a set of distributedmodules connected together as described herein, IMD 101 may be deployedproximate to a treatment or monitoring site.

While the embodiment of IMD 101 shown in FIGS. 1A-1B is implanted underthe scalp of patient 100 and may be used when the therapy provided topatient 100 includes neural stimulation of a brain, other embodiments ofIMD 100 permit the device to be implanted at many other locations withinthe body. In addition, IMD 101 includes a plurality of interconnectedmodules. Each module generally perform assigned functions.

In the typical embodiment depicted in FIG. 1B, IMD 101 includes threemodules, namely, a control module 103, a power supply module 104 and arecharge module 105. Control module 103 typically includes theelectronic components associated with the functions of IMD 101. In atypical implementation, control module 103 may include a hybrid circuitthat includes digital circuits such as integrated circuit chips and oneor more microprocessors, and analog circuit components. Accordingly,control module 103 may also be referred to as an electronic module.Power supply module 104 typically comprises one or more energy storagedevices, such as a rechargeable lithium ion battery. Recharge module 105typically includes one or more coils for transmitting or receivingelectromagnetic energy through the scalp. The transmitted energy mayinclude energy to be stored in power supply module 104. In someembodiments, the transmitted energy may also include communication, suchas information encoded in radio frequency transmissions.

Individual modules 103 and 104 may be encased in biocompatible metalshields such as titanium shield halves, and may be sealed againstcontamination. In addition, individual modules 103 and 104 may includeinsulation to electrically isolate the electrical components inside themodules from the metal shields. The modules are coupled to an overmold106 which may be made of a biocompatible material. Use of the term“overmold” herein is not intend to limit the invention to embodiments inwhich the overmold is a molded structure. Overmold may be a moldedstructure, or may be a structure formed by any process. In addition, oneor more coupling modules (not shown in FIG. 1A) may couple one or moremodules to one another.

In some embodiments of the invention, overmold 106 encases all modules103, 104 and 105. In other embodiments, overmold 106 is disposed over oraround the modules without encasing the modules. In further embodiments,overmold 106 acts as a “frame” to hold the modules in a fixed positionrelative to one another, but does not fully cover the modules. Somefeatures of the overmold, and variations on the shape of the overmold,are presented below. In general, the shape of the overmold depends uponthe arrangement of the modules. The overmold may be made of a variety ofmaterials, such as flexible silicone. The overmold may also include arigid polymer such as Ticothane surrounded by flexible silicone. Theinvention is not limited to these materials, however, and the overmoldmay comprise any combination of elastomeric and/or non-elastomericmaterials.

FIG. 2 is a schematic diagram illustrating an IMD 201 according toanother embodiment of the present invention. In this example embodiment,IMD 201 is arranged in a triangular configuration. IMD 201 includesthree separate modules: a control module 210, a power source module 211,and a recharge module 212. These three modules are connected together toconstruct IMD 201. IMD 201 also contains a set of lead connectionelements 213 that permit external leads to be connected to the controlmodule 210 as needed. The triangular configuration of IMD 201 permit IMD201 to possess a thin profile by spreading the modules over a largersurface area. In order to minimize the surface area compact, atriangular configuration is used. The configuration of IMD 201 may alsobe manipulated to conform to the shape of the location within a patientin which the device is being implanted. For example, implantation of IMD201 under the scalp of a patient may be accomplished if the overallshape of IMD 201 is curved to follow the shape of a patient's skull. Anynumber of shapes may be used to match a particular IMD 201 to animplantation location for a device.

FIGS. 3A and 3B are schematic diagrams illustrating an IMD 301 accordingto another embodiment of the present invention. In this embodiment ofIMD 301, a flat device is shown that consists of multiple modules. Thisembodiment may be used in other locations within a patient in which theimplantation location does not require such an exact match between thedevice and physical structures of the patient such as bone or muscle.IMD 301 may still be a modular device consisting of multiple modules asIMD 301 may provide a smaller profile when implanted as to not protrudeexcessively once implanted. IMD 301 need not be rigid, and in someembodiments the orientation of the modules of IMD 310 may changerelative to one another.

The flat embodiment shown in FIGS. 3A-3B may represent a device that maybe a pectoral implant that may be used to treat angina, to provide vagalnerve stimulation, or to provide cardiac rhythm management. Similardevices may be implanted into an upper buttock implant location, into anabdomen location, and into periphery. A device implanted into an upperbuttock location may be useful in a configuration for urological andgastrological implantation therapies. A device implanted into an abdomenlocation may be useful a configuration for providing pain, spasticity,and chemotherapy treatment. A device implanted into a periphery locationmay be useful a configuration for providing muscle stimulation, on-sitenerve stimulation, and diaphragm stimulation therapies. These devicesmay both provide therapies as well as provide a platform for sensingconditions present within a patient.

Additional alternate embodiments for implantable medical devicesimplemented according to principles of the present invention may alsoinclude non-electrical based therapies such as targeted introduction offluids and similar therapeutic agents using pumps and reservoirs. Oneskilled in the art will recognize that any number of implantable devicesmay be possible without deviating from the spirit and scope of thepresent invention as recited within the attached claims.

FIGS. 4A-4F are schematic diagrams illustrating exemplary configurationsand orientations of modules within IMD 401A through 401F (hereinafter410), according to various embodiments of the present invention. IMD 401consists of multiple modules that may be arranged into any number oforientations as shown in the various embodiments of FIGS. 4A-4F. Forreference, each IMD 401 is depicted deployed proximate to the skull of apatient, with leads 402A and 402B deployed through burr holes 402A and402B and coupled to IMD 401. The leads are coupled to the IMD via leadconnection modules 415A and 415B. As shown in FIGS. 4A-4F, the leadconnection modules may assume a variety of orientations relative toother components of IMD 401.

In each of these embodiments, IMD 401 has three modules as discussedabove in reference to FIGS. 1B and 2: a control module 410, a powersource module 411, and a recharge module 412. An overmold 413 at leastpartially covers the housings of control module 410 and power sourcemodule 411. The modules may be arranged into a number of orientations aslong as any interconnections between the modules may be routed withinthe device. The various embodiments include triangular configurations,as is shown in FIGS. 4A-4C, or linear configurations as shown in FIGS.4D-4F. In FIG. 4D, one of the three modules, such as the rechargemodule, is deployed as a tethered module 414 rather than being coveredby overmold 413.

The invention is not limited to the deployments of the lead connectionmodules shown in FIGS. 4A-4F. The lead connection modules may be locatedon various positions within IMD 401. Lead connection modules may beoriented, for example, to permit the leads to be routed to leadlocations in an efficient manner or to support management of excess leadlength. Any number of other orientations and alternate embodiments maybe constructed according to principles of the present invention andconsistent with the claims recited herein.

In each of the exemplary embodiments depicted in FIGS. 4A-4F, any twomodules may be interconnected via one or more coupling modules (notshown in FIGS. 4A-4F). The particular coupling modules may depend uponthe number of modules, the distance of the modules from one another, theamount of motion or displacement of one module from another, theexpected direction or directions of displacement, whether the modulesare arranged in a triangular, linear or other configuration, and so on.

FIGS. 5A-5C are schematic diagrams illustrating an exemplaryconstruction of an overmold used in construction of an IMD according tothe present invention. FIG. 5A illustrates that IMD 501 comprises a setof modules 510-512, a set of motion restriction elements, such as motionrestriction fibers 521. In FIG. 5A, motion restriction fibers 521 arecoupled to modules 510 and 511, and are covered at least in part byovermold 522. Overmold 522 typically includes a solid biocompatiblematerial. Overmold 522 may comprise an elastomeric material that is softand flexible, such as silicone. In addition or in the alternative,overmold 522 may comprise a non-elastomeric material that impartsrigidity to IMD 501. In one embodiment, for example, a non-elastomericmaterial in overmold 522 acts as a “frame” to hold the modules in afixed position relative to one another, and does not fully cover themodules. Overmold 522 covers, at least in part, the components andmodules within IMD 501 while providing a flexible structure that permitsthe device 501 to conform to fit each individual patient. Becauseovermold 522 is typically flexible, IMD 501 may benefit from motionrestriction devices such as motion restriction fibers 521, which providestructural integrity to device 501 once implanted into the patient.

Additional details regarding the set of motion restriction devices 521are described in co-pending and commonly assigned U.S. patentapplication entitled “REDUCING RELATIVE INTER-MODULE MOTION IN ADISTRIBUTED MODULAR IMPLANTABLE MEDICAL DEVICE,” assigned AttorneyDocket No.: 1023-333US01/P-11797.00.

FIG. 5B illustrates that the overmold 522 may include a non-elastomeric,or “hard” component 531 in addition to an elastomeric, or “soft”component 532. In FIG. 5B, the non-elastomeric component 531 is shapedto conform to the shape of at least one of modules 510-512 such that themodules may be restrained from motion by the non-elastomeric components.The non-elastomeric components 531 are typically made of a solidbiocompatible material such as polysulfone, and may also be made ofmetal such as titanium.

The non-elastomeric components 531 are utilized in locations in whichmotion is to be restricted. Any or all modules may be constrained by oneor more hard components 531. Overmold 522, including elastomeric andnon-elastomeric components, can be fabricated into a single structurebefore the modules 510-512 are inserted into the device 501.

Generally, overmold 522 serves a number of functions. For example,overmold 522 incorporates motion restriction elements within the device501, and attaches to modules and other elements to provide a unifieddevice. In addition, overmold 522 provides a smooth interface surfacefor the device as it interacts with the patient, and protects electricalconnections and feed through wires that connect modules to externalleads.

Overmold 522 may also include a durometric specific material to providedesired device qualities such as flexibility and structural integrity.In addition, the material used to construct overmold 522 may possess athermal conductivity characteristic to either act as a heat sink, or actas an insulator to shield the patient 100 from any excess heat from IMD501. Because IMD 501 may be constructed from a large number of modulesto perform a desired task, the materials selected for used inconstructing the overmold 522 may vary as needed by each embodiment.

FIG. 5C illustrates that overmold 522 provides sloped interface 541between an exemplary module 542 within IMD 501 and the patient's body.In embodiments in which IMD 501 is implanted within tight spaces, suchas under the scalp of the patient, sloped interface 541 provides asmooth transition and eases sharp edges that are known to cause possiblepoints of stress for tissue. An angle of interface from the patient'sbody and the sloped interface 541 can be approximately 135 degrees.

Additional details regarding the overmold 522 are described inco-pending and commonly assigned U.S. patent application entitled“OVERMOLD FOR A MODULAR IMPLANTABLE MEDICAL DEVICE,” assigned AttorneyDocket No.: 1023-332US01/P-11798.00.

In the exemplary embodiments depicted in FIGS. 5A-5C, any two modulesmay be interconnected via one or more coupling modules (not shown inFIGS. 5A-5C). In addition to considerations identified above, theparticular coupling modules may depend upon the configuration of theovermold, the configuration of elastomeric and non-elastomericcomponents; the presence of motion restriction devices, and so on.

FIGS. 6A-6C are schematic diagrams illustrating two distributed modules610, 611 having a coupling module 612 according to an embodiment of thepresent invention. In FIGS. 6A-6C, coupling module 612 provides a singledegree of freedom to move. In particular, coupling module 612 limitsmotion of modules 610, 611 relative to one another to a single axis.

IMD 601 shown in this embodiment is constructed from two individualmodules 610-611 that are physically linked using a flexible couplingmodule 612 that may also be referred to as a “power pipe module.” Thiscoupling module possesses a coupling body having a connection end ateach connection interface with a module. In a typical implementation, acoupling module 612 interfaces with a module by being coupled to ahousing of the module. In each of the three embodiments shown in FIGS.6A-6C, coupling module 612 constrains translational motion of one modulerelative to another. In FIGS. 6A-6C, coupling module 612 includes aflexible zone that is bendable.

In FIGS. 6A-6C, coupling module 612 is generally narrower than thedimensions of the modules 610-611. Furthermore, coupling module 612 maybe constructed of a more flexible material than the modules, resultingin some freedom of bending. In FIG. 6A, coupling module 612 is depictedas a distinct module coupled to two modules. In FIGS. 6B and 6C, bycontrast, coupling module 612 forms part of a unified structure withmodules 610 and 611. FIG. 6B illustrates the coupling module 612 asincluding a narrow zone between two compartments of a common structure,with a module deployed within each of the two compartments 610-611. FIG.6C shows the coupling module 612 as including a distinctly separateribbed element that separates the two modules 610-611 and thataccommodates some motion of the modules relative to one another.

With the freedom provided by coupling module 612, modules 610-611 may beoriented relative to one another, such that IMD 601 as a whole includesa convex surface. Coupling module 612 may be semi-rigid to permit theIMD 601 to be manipulated into a desired shape and then retain modules610-611 in a desired orientation. Alternatively, coupling module 612 mayflexibly permit modules 610-611 to move freely about an axis of rotation613.

Coupling module 612 defines at least one lumen or passageway. This lumen(not shown in FIGS. 6A-6C) permits components and elements in one module610 to be mechanically or electrically coupled to other components andelements in the other module 611. Coupling module 612 provides astructural support element that protects these connections betweenmodules from damage. Coupling module 612 may also include one or morehermetic interfaces between a module and coupling module 612 toenvironmentally protect the modules 610-611 from contamination. In someembodiments, coupling module 612 is hermetically fixed to at least oneof the housings of modules 610-611. In other embodiments of theinvention, coupling module 612 may be fixed to one or more modulesnon-hermetically.

FIGS. 7A-7B are schematic diagrams illustrating two distributed moduleshaving a coupling module with at least two degrees of freedom to move,according to an embodiment of the present invention. IMD 701 shown inthese embodiments includes two modules 710-711 that are physicallylinked using a coupling module 721 that may typically possess twodegrees of motion. In each of the three exemplary embodiments shown inFIGS. 7A-7C, a flexible coupling module 721 exists between the twomodules 711-712.

In these embodiments, the flexible coupling module 721 may flex abouttwo axis of rotation that correspond to dimensions of the of couplingmodule 721 that are most narrow. Coupling module 721 may rotate in apitch and yaw axis, for example, but not in a roll axis.

In FIG. 7B, IMD 701 includes a third module 713 coupled to anothermodule 711 via a second coupling module 722. Coupling module 722, likecoupling module 721, may support two axes of motion. As a result, theindividual modules 711, 712, 713 may be oriented relative to one anotherin three dimensions. Coupling module 722, like coupling module 721, maybe hermetic or non-hermetic. Coupling modules 721 and 722 may have, butneed not have, comparable degrees of flexibility.

FIG. 8 is schematic diagram illustrating an IMD 801 having twodistributed modules 811, 812 with a coupling module 821 that affordsthree degrees of freedom to move, according to an embodiment of thepresent invention. In FIG. 8, modules 811-812 are physically linked withcoupling module 821. Coupling module 821 affords some freedom to orientmodules 811-812 so that modules 811-812 are not co-planar. Modules 811and 812, may be moved closer or farther apart by flexing coupling module821 at bend 831A or bend 831B, or both. Modules 811 and 812, may also betwisted relative to one another by bending or twisting elongated section832. In the embodiment shown in FIG. 8, module 811 includes a notchedconnection point 833 that enables an enhanced range of motion.

The degree of motion is a function of the configuration of the couplingmodule, such its length or the number and placement of bends, and thematerial from which the coupling module is constructed. In oneembodiment, the coupling module is formed of titanium. Other materials,such as silicone, other metals such as stainless steel, or polymers suchas polysulfone, may also be used to construct the coupling module.Moreover, a coupling module may be constructed from more than onematerial. In general, a coupling module should be durable and reliable,and should be subject to bending or twisting without damage.

FIG. 9 is schematic diagram illustrating an IMD 901 with two distributedmodules 911 and 912 and a coupling module 921 having both a non-hermeticboundary 931 and a hermetic boundary 932. In this embodiment, theboundary between module 911 and coupling module 921 is non-hermetic. Incontrast, the boundary between module 912 and coupling module 921 ishermetic. Such an arrangement may make the fabrication of IMD 901simpler as it eliminates a hermetic interconnection boundary thatimposes cost, complexity and size limitations. In some circumstances,hermetic sealing of module components is unnecessary.

The nature of the hermetic interfaces above described refer to theinterfaces between modules and the coupling modules. As such, theoverall device 901 may possess no hermetic interfaces between thesemodules, and may permit passage of liquid or gaseous material betweenmodules, while the entire structure of IMD 901 remains hermeticallysealed from the patient. In another embodiment, one module, such as anon-hermetic battery may be enclosed within a hermetically sealed modulethat does not permit battery material to pass into a coupling module andany other modules. In this embodiment, the entire device 901 may also behermetically sealed from the patient. In a third embodiment, the variousinterfaces between all modules and a particular coupling module maypossess hermetic interfaces while the coupling module itself is nothermetically sealed to the patient. As such, a coupling modulecontaining an AC power connection between modules may not require ahermetically sealed coupling module with respect to the patient. All ofthese variations are contemplated to be within the spirit and scope ofthe present invention as recited within the attached claims.

In addition, the lumen defined by coupling module 921 need not be emptyor filled with air. In some embodiments, coupling module 921 may be backfilled with fluids and other materials. Such materials may, for example,offer some isolation of components disposed in the coupling module, ormay insulate, or may dissipate heat, or may absorb gases that may beemitted by a battery in a power supply module.

FIGS. 10A-10I are schematic diagrams illustrating exemplary couplingmodule shapes and configurations according to embodiments of the presentinvention. Coupling module 1001 provides a protected interconnectionvolume between two modules within a modular IMD. The particular shapefor the coupling module 1001 may be affected by the nature of theinterconnection between the two modules, the orientation of the modules,the size of the lumen, the desired degree of flexibility, and the like.One generally desirable characteristic of the coupling module is that itbe flexible enough to accommodate some motion of the modules relative toone another without becoming damaged. Some embodiments of couplingmodule 1001 may also provide structural protection and support for themodule interconnection.

FIGS. 10A-10C illustrate a coupling module 1001 having a single lumenconnecting two modules. FIG. 10A illustrates a round or circular lumen.FIG. 10B illustrates a semi-circular lumen. FIG. 10C illustrates arectangular lumen. The invention is not limited to a lumen having anyparticular cross-section, and includes coupling modules havingcross-sections not specifically shown herein.

FIG. 10D illustrates a coupling module 1001 that possesses a bellowssection 1002 as part of its structure. Bellows 1002 enhances theflexibility of coupling module 100I. In particular, the embodiment ofcoupling module 1001 depicted in FIG. 10D illustrates a coupling modulethat includes variations in the cross-sectional diameter thataccommodate motion along one or more axes of motion. The bellowsconfiguration in FIG. 10D is illustrative, and the invention includesembodiments that comprise corrugations, convolutions, or othervariations in cross-sectional shape that impart degrees of freedom ofmovement.

FIG. 10E illustrates that a coupling module 1001 of any configurationdiscussed herein may include multiple lumens. The lumens may provideindependent interconnection paths that are separate from each other.These multiple lumens permit the coupling module to provide connectionsthat are isolated from one other. In FIG. 10E, lumens 1003A and 1003Bare side-by-side. FIG. 10F illustrates a coupling module 100I havingcoaxial lumens. In FIG. 10F, the lumens include an inner conductor 1004Aand an outer conductor 1004B separated from inner conductor 1004A by adielectric 1005, such that coupling module is similar to a coaxialcable. In some embodiments, the lumens of a coaxial coupling module neednot include conductors or dielectrics. The invention encompassesembodiments in which lumens are configured in a concentric fashion.

FIG. 10G illustrates a coupling module 1001 that is a ring-likestructure having a plurality of separate conduit segments around thering. FIG. 10H illustrates another concentric arrangement for conduitsin which an inner conduit 1010 is separated from an outer conduit 1011.Finally, FIG. 10I illustrates that a coupling module may be arranged toinclude a helix-like structure. A helix-like structure may, for example,tend to permit more motion along some axes and less motion along others.

In some embodiments of the invention, a coupling module may include acombination of features shown in FIGS. 10A-10I. For example, a couplingmodule may include a straight portion and a helical portion, or multiplelumens and a bellows section. The invention encompasses all of thesecombinations.

FIGS. 11A-11M are schematic diagrams illustrating configurations ofmultiple modules having a coupling module interconnecting two modulesaccording to embodiments of the present invention. FIGS. 11A-11Millustrate various arrangements of interconnected modules used toconstruct an IMD. These arrangements illustrate some of arrangements forin-line and triangular configurations of the modules. These arrangementsillustrate use straight and helix-like arrangements of the couplingmodules. Finally, these arrangements illustrate interconnection ofmodules from adjacent module surfaces or sides as well asinterconnection of non-adjacent sides of modules.

Combination of various features gives rise to the exemplary arrangementsshown in FIGS. 11A-11H. In particular, coupling module 1101 may includea combination of straight, curved or helical sections when couplingmodule 1110 to module 1111. FIGS. 11I and 11J illustrate more rigidcoupling module 1101 arrangements between adjacent sides of two modules1110-1111. FIG. 11K illustrates that a coupling module 1101 may connecttwo modules 1110-1111 by bending around a third module 1112. Finally,FIGS. 11L-11M illustrate the interconnection of two modules 1110-1111using an S-shaped coupling module 1101. Embodiments in FIGS. 11L-11Minclude any arrangement and shape for a connection body used toconstruct a coupling module possessing at least one non-linear bend.

The invention is not limited to the particular coupling moduleconfigurations shown herein. The possible arrangements of IMD modulesand coupling modules is virtually unlimited.

FIGS. 12A-12C are schematic diagrams illustrating module interfaces witha coupling module according to an embodiment of the present invention.FIGS. 12A-12B illustrate construction of two distributed modules fromcase components 1201-1202, module end caps 1211-1212, and a flexibleinterconnection coupling module 1222. The module end caps 1211-1212, anda flexible interconnection coupling module 1222 are mechanically coupledusing weld joints 1231-1232. The module end caps 1211-1212 may becoupled to case components 1201-1202 with welds or braze joints. As isdiscussed above, these connections mat be either hermetic, as shown, ornon-hermetic. FIG. 12C illustrates a completed module end cap andcoupling module assembly 1241 that may be further coupled to two modules(not shown) to construct a modular IMD.

FIG. 13 is a schematic diagram illustrating the degrees of motionpresent in a multi-module IMD. For any two modules within a modularmedical device, motion between the two devices may be defined in termsof pitch motion 1301 (shown in side view), yaw motion 1302 (shown in topview), and roll motion 1303 (shown in end view). For the set of motionrestriction elements (not shown) discussed above, all three degrees ofmotion may be limited to prevent mechanical failures of interconnectionsbetween the modules during use of an IMD.

FIGS. 14A-14C are a schematic diagrams illustrating motion restrictionwithin various degrees of motion within a multi-module IMD. For any twomodules 1401-1402 within an IMD, motion restriction elements 1422-1423may be employed to constrain the relative orientation of modules1401-1402. Motion restriction elements 1422-1423 may be sufficient torestrain motion, thereby reducing the risk of potentially damagingstress upon a coupling module. In some embodiments, motion restrictionelements 1422-1423 are typically successful in adequately restrictingmotion in one or two degrees of motion. These degrees of motion aretypically along an axis in which the elements 1422-1423 possess most oftheir strength. For example, motion restriction elements 1422-1423 mayconstrain motion along a yaw and pitch axis but provide little or noconstraint along the roll axis.

FIG. 14A illustrates an embodiment in which the motion restrictionelements 1422-1423 include one or more physical members that physicallyinteract to restrain motion. FIG. 14B illustrates an embodiment in whichthe motion restriction elements 1422-1423 include one or more wire loopsthat oppose each other to restrain motion. FIG. 14C illustrates anembodiment in which the motion restriction elements 1422-1423 include afabric that physically restrains motion. In alternate embodiments,motion restriction elements may be used to constrain motion along one orall axes.

Additional details regarding the set of motion restriction elements1422-1423 described in co-pending and commonly assigned U.S. patentapplication entitled “REDUCING RELATIVE INTER-MODULE MOTION IN ADISTRIBUTED MODULAR IMPLANTABLE MEDICAL DEVICE,” assigned AttorneyDocket No.: 1023-333US01/P-11797.00.

FIGS. 15A-15B are schematic diagrams illustrating an exemplaryinteraction of components of an IMD that are part of an overmold 1522,which includes one or more soft or elastomeric components 1532 and oneor more hard or non-elastomeric components 1531, which interface with acontrol module 1510. Non-elastomeric component 1531 may be shaped tomate with the module 1510 to provide motion restriction for the module.Non-elastomeric component 1531 may be mechanically connected to othermodules using a motion restriction element (not shown). The overmold1522 covers all of these components in this embodiment. A through hole1551 may be located through the through the non-elastomeric component1531 and elastomeric component 1532 to provide an attachment point forthe device 1501. In some embodiments, IMD 1501 may be anchored in placeusing bone screws or other anchoring devices. Through holes 1551 permitIMD 1501 to be mechanically anchored to the patient once the device 1501is positioned at a desired location. In the embodiment shown in FIG.15A, a bone screw inserted into through hole 1551 would seat againstnon-elastomeric component 1531, but the invention encompassesembodiments in which a bone screw would seat against another component,such as control module 1510.

FIG. 15B illustrates a top view of the device 1501 having elastomericcomponent 1532 of overmold 822 covering the non-elastomeric components1531 that frame control module 1510. The through hole 1551 used as anattachment point is shown as part of non-elastomeric component 1531 thatis covered by elastomeric component 1532. The shape of non-elastomericcomponent 1531 and control module 1510 are shown as being rectangular inthis embodiment. However, one skilled in the art will recognize that anyshape for non-elastomeric component 1531 and control module 1510 may beused without deviating from the spirit and scope of the presentinvention.

In addition, overmold 1522 is shown in FIGS. 15A and 15B assubstantially or completely encapsulating module 1510. However, overmold1522 may also merely surround the module 1510 but not cover the top ofthe module that is surrounded by the hard component 1531. Such anarrangement may result in a smaller profile of the overall IMD.

A coupling module (not shown) passes around and through many of theelements of the overmold. This coupling module may be, but need not be,constrained within overmold 1522. In general, the coupling module may beexpected to flex during implantation and use. In some embodiments of theinvention, the coupling module may be routed in a channel (not shown)within the overmold.

Additional details regarding the overmold are described in co-pendingand commonly assigned U.S. patent application entitled “OVERMOLD FOR AMODULAR IMPLANTABLE MEDICAL DEVICE,” assigned Attorney Docket No.:1023-332US01/P-11798.00.

FIGS. 16A-16B are a schematic diagrams illustrating a multi-module IMD1601 having a triangular module arrangement according to the presentinvention. FIG. 16A illustrates an exploded view of IMD 1601. FIG. 16Billustrates a perspective view of IMD 1601. In this embodiment, anothertriangular arrangement of modules is shown with an overmold 1622covering or at least partially encapsulating the modules. In thisembodiment, overmold 1622 comprises a distinct slope interface 1641 thatsurrounds the periphery of IMD 1601. In this embodiment, slope interface1641 is shown as a separate physical structure, such as a flexible bandor ring. A coupling module 1651 is shown connecting two modules1610-1611 without being restrained by the overmold 1622.

While the above embodiments of the present invention describe a couplingmodule of a modular IMD, one skilled in the art will recognize that theuse of a module structure are merely example embodiments of the presentinvention. It is to be understood that other embodiments may be utilizedand operational changes may be made without departing from the scope ofthe present invention as recited in the attached claims. Although thedimensions of different embodiments of coupling modules may vary, thedimensions of typical coupling modules are such that the coupling moduleneed not be responsible for the thickest portion of the IMD.

As such, the foregoing description of the exemplary embodiments of theinvention has been presented for the purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed. Many modifications andvariations are possible in light of the above teaching. It is intendedthat the scope of the invention be limited not with this detaileddescription, but rather by the claims appended hereto. The presentinvention is presently embodied as a coupling module of a modular IMD.

1. An implantable medical device comprising: at least two modules, eachof the modules comprising a respective one of a plurality of housings,wherein the at least two modules are spaced apart and each housingprovides a respective space within the housing; a plurality ofelectrical components, wherein each of the housings contains one or moreof the electronic components within the space of the housing; and acoupling module coupled to each of the modules, the coupling moduledefining at least one lumen between the housings, the at least one lumenconnecting the spaces within at least two of the housings.
 2. Theimplantable medical device of claim 1, wherein the coupling modulepermits motion of the at least two modules along at least one axis ofmotion.
 3. The implantable medical device of claim 1, wherein thecoupling module permits motion of the at least two modules along atleast two axes of motion.
 4. The implantable medical device of claim 1,further comprising an overmold that at least partially encapsulates eachof the housings and the coupling module.
 5. The implantable medicaldevice of claim 1, wherein at least one of the at least two moduleshouses control electronics for controlling the implantable medicaldevice and another of the at least two modules houses a battery.
 6. Theimplantable medical device of claim 1, wherein no hermetic interface isbetween the at least two modules along the coupling module.
 7. Theimplantable medical device of claim 1, wherein the coupling module isfixedly coupled to the at least two housings.
 8. The implantable medicaldevice of claim 1, wherein the coupling module is hermetically attachedto the at least two housings.
 9. The implantable medical device of claim1, wherein the coupling module is made of a metal that forms the atleast one lumen.
 10. The implantable medical device of claim 1, whereinthe at least one lumen comprise co-axial lumens.
 11. The implantablemedical device of claim 1, wherein gaseous material is permitted to passthrough the lumen between the spaces of housings of the at least twomodules.
 12. The implantable medical device of claim 1, wherein thecoupling module defines one of a circular cross-sectional shape, asemi-circular cross-sectional shape, and a rectangular cross-sectionalshape.
 13. The implantable medical device of claim 1, wherein thecoupling module includes a bellows section.
 14. The implantable medicaldevice of claim 1, wherein the coupling module is fixedly coupled to atleast one of the at least two housings with a weld joint.
 15. Theimplantable medical device of claim 1, wherein the coupling modulecomprises at least one bend.
 16. The implantable medical device of claim1, further comprising a conductor passing through the at least one lumenthat electrically couples electrical components between the at least twohousings.
 17. The implantable medical device of claim 1, wherein theelectrical components include a battery, a telemetry module, and aprocessor.
 18. The implantable medical device of claim 1, wherein thecoupling module is constructed of polymer.
 19. An implantable medicaldevice comprising: two housings spaced apart, each housing providing aspace within the housing; a plurality of electrical componentsdistributed between the housings, the electrical components containedwithin the spaces of the housings; and a coupling module coupled to eachof the housings, the coupling module having a lumen connecting thespaces of the housings.
 20. The implantable medical device of claim 20,wherein the coupling module permits the housings to move relative to oneanother.